Bottom Line:
Here, we investigate the effects of chronic ethanol on neuroinflammation and neurodegeneration triggered by toll-like receptor 3 (TLR3) agonist poly I:C.Escalating blood and brain proinflammatory responses were found with ethanol, poly I:C, and ethanol-poly I:C treatment.Ethanol potentiation of poly I:C was associated with ethanol-increased expression of TLR3 and endogenous agonist HMGB1 in the brain.

Affiliation: Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, NC 27599, USA.

ABSTRACT

Background: Increasing evidence links systemic inflammation to neuroinflammation and neurodegeneration. We previously found that systemic endotoxin, a TLR4 agonist or TNFα, increased blood TNFα that entered the brain activating microglia and persistent neuroinflammation. Further, we found that models of ethanol binge drinking sensitized blood and brain proinflammatory responses. We hypothesized that blood cytokines contribute to the magnitude of neuroinflammation and that ethanol primes proinflammatory responses. Here, we investigate the effects of chronic ethanol on neuroinflammation and neurodegeneration triggered by toll-like receptor 3 (TLR3) agonist poly I:C.

Mentions:
NADPH oxidase (NOX) is a family of oxidases known to produce superoxide and NOX is thought to be involved in neurodegeneration [40]. To determine the role of NOX in TLR3 agonist proinflammatory responses, we investigated the expression of NOX gp91phox, the catalytic subunit of phagocytic oxidase commonly associated with proinflammatory responses. Poly I:C induced NOX gp91phox mRNA 2 to 3 fold (Figure 5A) and NOX gp91phox + IR by manyfold more in cortex and hippocampal dentate gyrus (Figure 5B). Ethanol treatment produced a non-significant trend toward an increase in NOX gp91 mRNA, but did increase gp91phox + IR above control levels to about half of that found with poly I:C alone. Ethanol potentiated the poly I:C TLR3 responses with both NOX gp91phox mRNA and NOX gp91phox + IR increased in cortex and hippocampus (Figure 5). Double antibody studies with cell specific markers and confocal microscopy indicate that ethanol-poly I:C-induced NOX gp91phox + IR is colocalized with neuronal marker (MAP-2) and a microglial marker (Iba1) but there is little colocalization with astrocytic marker (GFAP) (Figure 6). These results indicate that TLR3 activation increases brain NOX gp91phox.

Mentions:
NADPH oxidase (NOX) is a family of oxidases known to produce superoxide and NOX is thought to be involved in neurodegeneration [40]. To determine the role of NOX in TLR3 agonist proinflammatory responses, we investigated the expression of NOX gp91phox, the catalytic subunit of phagocytic oxidase commonly associated with proinflammatory responses. Poly I:C induced NOX gp91phox mRNA 2 to 3 fold (Figure 5A) and NOX gp91phox + IR by manyfold more in cortex and hippocampal dentate gyrus (Figure 5B). Ethanol treatment produced a non-significant trend toward an increase in NOX gp91 mRNA, but did increase gp91phox + IR above control levels to about half of that found with poly I:C alone. Ethanol potentiated the poly I:C TLR3 responses with both NOX gp91phox mRNA and NOX gp91phox + IR increased in cortex and hippocampus (Figure 5). Double antibody studies with cell specific markers and confocal microscopy indicate that ethanol-poly I:C-induced NOX gp91phox + IR is colocalized with neuronal marker (MAP-2) and a microglial marker (Iba1) but there is little colocalization with astrocytic marker (GFAP) (Figure 6). These results indicate that TLR3 activation increases brain NOX gp91phox.

Bottom Line:
Here, we investigate the effects of chronic ethanol on neuroinflammation and neurodegeneration triggered by toll-like receptor 3 (TLR3) agonist poly I:C.Escalating blood and brain proinflammatory responses were found with ethanol, poly I:C, and ethanol-poly I:C treatment.Ethanol potentiation of poly I:C was associated with ethanol-increased expression of TLR3 and endogenous agonist HMGB1 in the brain.

Affiliation:
Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, NC 27599, USA.

ABSTRACT

Background: Increasing evidence links systemic inflammation to neuroinflammation and neurodegeneration. We previously found that systemic endotoxin, a TLR4 agonist or TNFα, increased blood TNFα that entered the brain activating microglia and persistent neuroinflammation. Further, we found that models of ethanol binge drinking sensitized blood and brain proinflammatory responses. We hypothesized that blood cytokines contribute to the magnitude of neuroinflammation and that ethanol primes proinflammatory responses. Here, we investigate the effects of chronic ethanol on neuroinflammation and neurodegeneration triggered by toll-like receptor 3 (TLR3) agonist poly I:C.